Exploring Convection Currents:

ObjectiveTo construct several models to demonstrate the principle of convection, and to use your observations to explore the role convection plays in the development of atmospheric circulation and ocean currents.

Materials Needed per Lab Group:

1 Clear Plastic Box

1 Beaker, 50 ml

1 Wood Block

2 Pipettes

6 Styrofoam Cups

8 Plastic Lids (spacers)

1 Plastic Spoon

Student Study and Analysis Sheets

Shared Materials

Food Coloring

Salt

Water (hot and cold)

Ice Cubes

Graduated Cylinder, 100 ml

Colored Pencils

Periodic Table

Procedure – Part 1

Setup A 1. Fit two plastic lids on each of 4 Styrofoam cups. Set the clear plastic box onto the four Styrofoam cups as shown in figure 2. Carefully fill the box with cold tap water to within 3-4 cm from the top. Let the water calm before proceeding. 2. Using the pipette, carefully place 3 spots of red food coloring on the bottom of the box as shown in figure 2. Insert the pipette all the way down to the bottom of the box before squeezing out the dye. Each spot should be about 2-4 cm in diameter. Try to minimize disturbing the water as you insert and remove the pipette.

3. Fill one empty Styrofoam cup with hot water and then carefully position it beneath the center dye spot. The plastic lid spacers you fitted on the corner cups should provide you with enough clearance to gently slide the cup with to water under the spot.

4. Now position yourself so that you can view the box from the side at eye level, and observe what happens to the 3 spots over the next 5 minutes. Be sure to look for changes in all 3 spots. Write your observations below.

5. Sketch what you observed in diagram 1 below. Use arrows to show the direction of flow.

6. Using two hands under the box, carefully empty the water into a sink and begin Setup B.

Observations:

The Dye rises up

Little bubbles form on the bottom of the container

The dye circles connect towards each other

Since there is low pressure on the two corner dots, they go away from each other

The water slowly get's full of dye

Setup B 1. Repeat procedures 1 & 2 from Setup A to set up the box one again.

2. This time, fill two cups with hot water and position them beneath the two outside spots. Observe what happens over the next 10 minutes, and then sketch what you observed in Diagram 2 below. Be sure to look for changes in the middle spot. Use arrows to show direction of flow.

3. Carefully empty the water from the box into a sink, and begin Setup C.

Setup C 1. Set up the plastic box once again as in Setups A & B and fill with cold tap water to within 3-4 cm of the top. Let the water become calm. Next, place two spots of food coloring near one end of the box. Position one cup of hot water beneath each spot.

2. Use a plastic spoon to obtain a blue ice cube from your instructor. Carefully set the cube into the water at the opposite end of the box from your dye spots. Use the spoon to steady the cube until it stops moving.

3. Position yourself at eye level with the side of the box, and observe the water as the ice cube melts.

Follow-Up Questions:

1. During the lab, what effect did the cups of hot water have on the density of the water directly above them? (hint: think about particles moving) The density went down, it decreased as the water became warm.

2. What happened as a result of this change? The dye in the middle rose in both directions, left and right, to the top.

3. You may have noticed convection cells in a pot of boiling macaroni. Put arrows on the dashed lines in Figure 4 to show the direction of the flow in the pot. The hottest part of the burner is beneath the center of the pot.The macaroni is going to float to the top of the pot.

4.- Which situation would result in a decrease in the atmospheric pressure at the earth surface?The air gets hot and begins to rise.

5.-Above which area would the air become hotter in the afternoon?A retaining pond next to the parking lot.

6.-Above which are would you find the lowest air pressure?The retaining pond.

7.- Based on this arrangement, would you expect a breeze to blow toward the parking lot , or away from it ?It will blow towards the parking lot.

8.-Why the wind would blow in from the sea toward the land during the afternoon?The cold water air goes into the hot land, while this is releasing the hot air.

9.- A "monsoon effect " may happened in the summer as air over a continent becomes much warmer than air over the ocean. A)As air over the continent becomes hotter , it will begin to rise .B)This cause lower pressure over the continent.C)The flow of air will be toward the center of the continent.

10.-Which region in our atmosphere is heated most intensely by the sun?The equatorial region.

11.- As air near the equator rises , does this become an area a higher or low pressure?Low pressure.

14.- Wind is considered to be a form of "solar energy"Wind is consider a solar energy because Solar Energy plays a huge role in the world.This is because the sun causes uneven heating ,which leads to convection, which is where the air rises up . Later in the area the air rises and now becomes an area of low pressure.

Notes:-Energy comes from the sun. -Radiant energy is reflected by water droplets and dust particles in the atmosphere.-Some energy is caused by wind currents, cloud formation, and severe storms.-Physical property of substances are called heat capacity.

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